Best Practices for Joining Additional Columns into an Existing Table Using PROC SQL
Best Practices for Joining Additional Columns into an Existing Table Using PROC SQL Best Practices for Joining Additional Columns into an Existing Table Using PROC SQL When working with large datasets, it's common to add new columns from another table to an existing table using SQL. However, many programmers encounter the challenge of recursive referencing in PROC SQL when attempting to create a new table that references itself. This blog post discusses the best practices for adding columns to an existing table using PROC SQL and provides alternative methods that avoid inefficiencies. 1. The Common Approach and Its Pitfall Here's a simplified example of a common approach to adding columns via a LEFT JOIN : PROC SQL; CREATE TABLE WORK.main_table AS SELECT main.*, a.newcol1, a.newcol2 FROM WORK.main_table main LEFT JOIN WORK.addl_data a ON main.id = a.id; QUIT; While this approach might seem straightforward, it leads to a warning: "CREATE T...